Air-pump stroke and pressure indicator



April 3, 1928.

J. w. HANNAN -AIR PUMP STROKE AND PRESSURE INDICATOR Filed Dec. 16. 1926 5 Sheets-Sheet 1' M 4 7 m 41% A, m i 1 0 a 6 4 i A 1 L E\\ \R\\\ 7 E L l I J E April 3, 1928. 1,664,557

J. W. HANNAN AIR PUMP STROKE AND, PRESSURE INDICATOR April 3, 1928.

J. w; HANNAN AIR PUMP STROKE AND PRESSURE INDICATOR Filed Dec. 16. 1926 s Sheets-Sheet 3 .lEl

Jame s W. H awn an 40 tion-al view taken through details of Patented Apr. 3, 1928. i

UNITED STATES PATENT, OFFICE.

, .iAMns HANNAH; or ooFFEYviL E, KnNsAs.

lim-ruivrrsrnoxn AND PRESSURE INDICATOR.

Application filed December is, 1926. Serial No. 155,316.

This invention relates to improvements fortesting the efliciency within cylinders wherein pistons operate, whether the pres sure be superatmospheric or subatmospher-ic.

The primary objectof-the invention is the provision of apparatus for testing the efliciency of air pumps and the like; being especially adaptable for'use in testingv the efiiciency of locomotive compound-or: single stagecompressors, in order to determi'ne specifiefaults in the operation thereof, suclras leaky packing rings; leaky valves;

clogged air passages clogged strainers;

sure air cylinder: the improved device when used. in this counection"having agauge 'a's-n sociated therewith tor. s'determin'ing -super- :itmospheric pressures existing in the cylinder of each limit of stroke ofthe'piston therein. V. a Figure 3 is a front elevation of: the tubular casing of the improved device.

Figure 4 is a fragmentary vertical secconstructi on of the improved device.

Figure is a fragmentary sectional view taken through the upper endofthe improved device. as mounted in the lowerend of an air cylinder. showing itsrelativecooperation of parts and its association with the piston. v

Figure 6 is a tragmentarysectional view taken substantially on: the line 6&6 of Figure 1. 1

' Figures 7. 8 and 9' are sectional views taken substantially on their respective -lines in Figure 5 ot-the drawings.

Figure 10=is a sectional view taken through n iheretarder which is. associated with the gauge portion of the improved device'tor elevation of the imeral efficiency of operation of the highpresbuffing the air action. of. the indicators ofthe gauge, to prevent damage thereto,

- Figure 11 is a sectional view taken through the valve illustrated in Figure 10, in a differently adjusted position for venting air to the atmosphere from the cylinder, to aid the blowing out of air passages and the ire. I v I Figure ;12-is a transverse sectional view taken substantially {on the line 12'-12-0f Figure 10.-

Figure 13 is a, front elevationof the im proved device, showing the same. as applied to the, low air pressure cylinder side of a .cross compound air compressor, or as used. in-connection with a single stage air-compressor. and in thisinstance the type ofgaugeis different than the'gauge used in the illustration of Figure 2, since it will have to register-' superatmospheric pressure and subatmospheric pressure or vacuum. I

- Figure 14 is .a front elevation of the dial and indicators of the type of gauge illustrated in use inFigure 13.

Figure15-is a fragmentary sectional view of a detail of the invention used during the assemblage of the device-to the cylinder.

In the drawings, wherein similar reference characters designate corresponding parts throughout. the several views. the letter Av may generally designate the improved de- .vice which is preferably used for testing the general efliciency ot'air cylinders of locomotive air pumps tomdetermine lacktof efliciency of parts; the improved device including a supporting body construction B wherein 'a reciprocating construction C is mounted in a. cooperative relation with respect to the piston D when the device'A is .assembledupon an air cylinder E or F; the reciprocating constructionG having means I to cooperate witha valve construction H in order to vent the air pressure from the air cylinder" at-difl'erent intervals thru valved lines K or L; for definitely operating. the di'flerent indicator arms of the gauges M or N, as the case may be. I

The United States Interstate Commerce Commissionfrequires that an orifice test be made of locomotive air p'umpsat intervals of three months. The tests now in vogue are entirelyunsatisfactory', which is proved )by thefact that locomotive engineers are constantly making complaints that while their air purnps will suit the requirements of the orificetest,yet the air pumps of their the trouble.

, sageway passageway 33 w an annular flange a part of the push rod compressors will not supply enough air to properly handle the trains safety. Certain rules are also laid down by the makers of locomotive air pumps or compressors, to determine the troubles of the air pu1np,but in the main they leave the way open for a large amount of guess work'as to the location of ith the improved device herein described, the effieiencyof the pump can be tested, and the trouble determined by reference to what the efficiency of the particular air compressor being tested ought to be. I Referring to the invention, the construction B includes a anain body portion 20, comprising a short tubular nipple having a pas- 21 therethrough, and at its upper end being externallyscrew threaded at 23 for detachable connection in the internally screw threaded opening 24, which comprises theorifice in the casing or housing 25 of the air pump or cylinder E or F to be tested. The lower end of the body 20 is internally screw threaded'at 27 for detachably receiving the screw'threaded portion 28 of a guide 30, which extends upwardly thru the'passageway 21 and itself is provided with a for snug sliding of the upper push rod'portion 35 of the reciprocating construction G. The guide 30 adjacent the screw threaded portion 28 is provided with 31 which abuts against the outerend of the body portionQO, and the annular flange 31 is recessed to provide a screw threaded socket 35 adapted to detachably receive therein the upper externally screw threaded end of a spring barrel 38, which maybe held in such position by a lock nut 39. Referring to the reciprocating,construe t-ion G, the same includes a cross head'40 including upper and lower portions 41 and 42 held together by a screw threaded pin 44; the upper portion 41 of the cross head 40 having the lower or outer end of the push rod 35 rigidly connected therewith at 45. Thecross' head 40 is provided with a transverse "screw threadedj opening 48 therethrough for detachably receivinga headed pin 49, the head of which elongated slot 50 provided longitudinally of the barrel 38, and tern'iinating short of the ends of said barrel, so that. the head of the pin 49 slides along the slot 50 during'reciprocation of the cross head 40,, and this head projects beyond the external circumference of the spring barrel 38, to cooperate with valve'operating levers 52 and 53 disposed at the ends of travel of the cross head, although positioned externally of the spring barrel38.

The cross head portion 42 at the end thereof opposite the push rod 35 is provided with a detachable rod 52 which may be considered 35 since the'same is operably removable therewith, and this red portion '52 extends axially thru the spring barrel 38 in a circumferentially spaced redegree extends thru an jwith the ducts 76 and which is detachably mount-- i rod 35 into the chamber of theair cylinder E or F, as the case may be, againstthe piston D operating therein, when'the device A is attached to the air cylinder in the relation described.

I At this point it well to state that the gauge of the device A is adaptedto-register the air pressure-at the limits of movement ofthe cylinder chamber. These the ends of I the piston D, and consequently the piston Din pressures Wlll be [different at movement of the gauge M which is used for gauging the pressures in'the high pressure air cyhnden of a cross compound air compressor should embody a mechanisnifor operating two in dicator arms: 60 and61. This type of gauge may be the conventional duplex air gauge well understood as being used in connection with air brake equipment of locomotives, and the same has two passageways leading thereto for receiving air pressure arms 60 and 61 to indicate diiferent air pressures, at about-the same time. The dial 62 of the gauge M is graduated to anyapproved or number of pounds, and the arms 60and 61 are bothpivoted on the same although independently tionwell understood in actuated in a relabracket 68 to the body portion 20 of the housing construction of-the improved deviceA, as illustrated in the drawings, so that the same faces forwardly when the de cuinstancesto be subsequently described. 7 'An extension 70 is portion 20 of the body improved device. laterally side, and providing a passageway 71 therein open at both ends thereof, wherein a'cylindrical shaped valve seat 72 is fixed. and wherein a cylindrical shaped valve 73 is slidable in a line parallel with the push rod 35. The valve seat 71 is preferably provided with spaced ports sag'eway 21 of the body. 20 above defined.

'Due to the fact that the guide 30 is of less diameter than the passageway 21, an annular this art, andthey are preferably differently colored to contrast them from each other. The casing 65 of the I gauge M is detachably connected bysuitable I '1 I 74 and 75 therein, one above the othen'which respectively align 77 leading to the pas to operate the lUll' axis,

vice A is attached to an air cylinder, for indicating the different air pressures under cir-' formed. on the body construction of the extending to one gether bya bolt 99 as a space is provided between the passageway 21and the external eircumtereneeof the rodguide 30, wherein .air enters-from thegoylin-f der chamber, and passes into the ducts 76 and 77 and thence thru the ports 74 and-v to the valve 72. The valve 72 is provided with spaced annular grooves 79 and 80 there in, spaced for a greater distanceapart than are the ports 74 and'75, so that only-one'or the other ofsaid'groovesniay' align with their respective ports 74' 01' 75. (Thus, when the port 75 aligns with the groove'80 the port 74 is closed to the groove.79, as illustrated in-Fig'ure 5, and vice-'versa the'condition may'occur, as illustrated in Figure 4,

where the port 74 aligns with the groove'79, and the port? 5 is closed toits groove 80.

Referring now to the connection of the valve with the gaugeM or N, as the case maybe, tubes or conduits and 86inay be provided, which lead to the gauges Mor N,

as the case may be, forroperating the two indicators thereon, these conduits 85ran'd '86 having suitable connections at 88 and 89, best illustrated in Figure 6 01 the drawings, so that the groove 80 may coop'erably align with the-port90 in the connection 88*to perv 1111i? air to flow from the ductz77 thru the port 75 and thence thru the groove 80 into the duct 90 and into the tube 85'. Similarly, the connection 89 has a duct 93 therein with which the groove 7 9 in the valve 7 2 may be aligned, but only in event the groove 80 is out of alignment with the port 75 above men tioned and its. duct 90, as can readily" be understood-from Figure 6' of'the drawings.

The conduits 85 and 86 respectively lead to suitableeports (not shown) of the gauge M or -1 ,'asthe case may be, in order that the air pi'essure'in the conduit 85 may operate the indicator arm 60, and the air pressure in theconduit 86 may operate the indicator.

arm 61.

Referring to the operating'means of the valve construction H, the valve 72 has a valve rod 95 connected therewith, and extending downwardly parallel-with the push rod 85, at its lower end being supported by a suitable adjustable bracket 96 connected on the barrel 38; andintermediate its ends said valve rod 95 being slidablyreceived within thepassageiway 97 o f a bracket 98 which is also carried by the spring barrel 38, as illus trated in Figure 4 of the drawings. Thus the valve rod and valve are guided for movement in a line parallel with the movement of the reciprocating construction C, as is per fectlyv obvious.

The bracket arms 96 and 98 may be of any approved construction, as illustrated in Figure? ofthe drawings, and they may each include a split sleeve adjustably held to- 7 means to securely clamp them in the desired position along the spring barrel. 7

opening 135, which extends in a Thebrackets 96 and '98 -respectively' supportadjustable lever supporting arms 1001 and 101, respectively facing towards each other, and including square shanks adjustable in suitable openings 102 transversely provided thru their respective brackets, and

these shanks being held in adjusted position by means of set screws 103, best llustrated in Figure 7 The bracket arms and 101 a respectively support th'e pivoted levers 53 and 52, intermediate the ends of said levers thelevers being radially positioned wlth respect tothe spring barrel and being detachably orpivotally supported on pins 107 each with a short end 108 extending at one side ofthe pivot pin towards the barrel 38-, and

at their opposite ends having bifurcated extensions 109 which straddle'the valve rod 95.

The valve rod 95 is adjustably provided with collar-s 110 ill'ld'lll against which the levers 52 and 53 respectively operate; sai

collars being held in adjustable.relation'oi the rod 95 by set screws 112; the collar 11L is positioned a recoil bufling tions 12]: and 122 at opposite ends thereof in the FOSPBCtlVC'CODLlHit in whiclrpositioned,

and being provided with, ducts 124 and 125 tor communicating with the passageway of the conduit in which positioned; Sa1(l'(lil(3tS 124 and 125 leading into a seat126 wherein theval-ve member 127' is positioned to regulate'the flow of air pressure 'to'the gauge-0r to the atn'iosphere. i

The valve member 127 conical type, supported in its's'eatin any approvedmanner; the same havinga-port 130 which may be aligned .with the. duct 124.- during pressure reading, or which may upon a 90 turn of the valve 'member 127 be aligned with 120, which leads'to theatmosphere as illustrated in F ignre'll. The valve member127 also includes a right angled port 133, which during either of the positions above men tioned for the poi t'130 is aligned with the port 125', to receive-air pressure. Preferably is a tapered axially in the valve member-127 I converging relation from the port130' to theport 133 and which is provided .for the tapered end Ora needle valve .138, which" is adjustably a port 132 in'the valve body is of preferably the i in which cylinder variable effect this assemblage, the rod spring barrel.

justment of the needle valve 138, the degree.

of the opening 135 may be regulated, in orle-r tobutf the'pressure act-ionjttrom the air cylinder to the indicators of the pressure gauge, and thus preventing destruction to the mechanism. in the pressure gauge. lhc valve member .127 is turned independent of adjustment oi? the valve 138, by means of a handle 1&0. I

Referring to operation oil? the improved device, as used on the high pressure air cylinder ota cross compound air compressor, and superatmospheric pressures exist during operation of the piss ton D therein, the housing body construction B ismounted with respect to the air cylinder in theielation illustrated in Figures 2'and 5, and as above described. To is pushed downwardly into the spring barrel, to com press the-spring 59, to the point where the transverseopening illus'strated in Figure 15, onrod 52 forced beyond. the cap 55, and a cotter pin is inserted tlnru the opening to hold the spring compressed. and the reciprocating construction C downwardly in the The housing body 20 is then. inserted into the orifice opening 2% and screwed in place, ant. after which the cotter 7 portion of head of the pin e9 will ride pin is released and the rod 35 will then abut against the bottom of the piston D, or the rod which connects to said pistornin the relation of parts-illustrated in F ure 5,

e whereihe top edge 1250i the rod 35 is shownv asabutting against the bottom end of the piston rod of the pistonD. Upon operation of the compressor, according to present practice, the push rod 35 will, be reciprocated with the piston D, since the piston D on the downstroke will force the 35 down andupon the upstroke of the piston the force of the spring 59 expanding will compel the push rod 35 to follow the piston travel, as is perfectly obvious. Assuming the piston D to be coming down, the projecting along the slot 50 of the spring barrel. and at the very lowest movement of the piston. stroke the headed lever end 108 of the lever 53, and immediately thereafter the piston D will elevate and the spring force will, cause the head 01 the pin 19 to ride beneath the projecting end 108 of the leverr53, causingtheend 109 of the lever 53 to move downwardly against the collar 111, to pull the piston rod 95 ,downwardly and'the valve 72 therewith, and when the uppermost: groove 79 of the valve has aligned with the port 74, the headed end of the pin 49 will slip over thelever 53 and the air pressure between the piston D and the lower end, of the cylinder will pass thru the passageway 21 ,andthru the duct 76, thru the piston D therein.

stroke of the cylinder piston D continues,

push rod the pin 1-9 will. pass below the I theport 74, into the groove 't't), thru the open iug 93. into the conduit 86, and thence past theiretarding valve R in that conduit and into, the gauge Mrwhere the same will actri; ate one of the indicator arms, say

the indicator arm for indicating the pressure which exists in the high nressurerylinder E- at the outermost limit of. the stroke of the pnslrrod will'ot course ride therewith. incident to the action of the spring 59, and the-head extension of the pin 49 will ap-.

preach the lever 52 anddride over the cam surface thereof to a point above the end 108' of thelever 52, and the: piston Dwill then be .at the innermost or top end of its stroke, and immediately thereafter the piston D com'mencesits outstroke and will-engage the end108 of the lever 52and force the end 1112 upwardly against the collar 110th move the valverod 95 and the valve .72 13l1G16\ 'ith until the groove 80 is-alignecl with the port 75, and in which case the compressed air on the cylinder E will flow into the duct 77in the relation above described, and. thence thru the port .7 5, into the groove 80, into the duct 90 and into the conduit ,85, and from thence pass the retarding valve R and into. the gauge M, where the same actu- As the inst-rokeor up in the line 85,"

ates the indicator arm 61 to registerthe pressureexisting in the cylinder the stroke of the piston D. From the above it is apparent that the device A is best used to measurethe air pressure in. the high pressure cylinder the limits of the stroke of the piston in the cylinder.-

E at the top of In order to prevent. an eccentric operation) of the valve 72 upon its actuation thru the lever 52, a. spring retaining-arm 130 is carried by the bracket 98, having a notch 131 therein in which the end portion 112 of the lever 52 engages after the lever 53 has been actuated by the head of theevtension pin49, and having an upper notch 132 which receives theportion 112 of the lever 52 after the latter has been operated by the head of the extension pin l0 to align the groove 80 with the port- 75 in the relation of parts illustratedin Figure 5 of the drawings. i

The form of invention illustrated in Figures 13 and 1s differs trointhe construction above described in that the sameisadapted for use on thelow pressure cylindersot air compressors, or on the-single stage compressor, in which during the instroke of the; piston a partial vacuum is created in the cylinder chamber, so that the cylinder chamberisthen under subatmospheric pressure. For this a special gauge N is provided which has indicating respectively cooperating with the pressure and .vacuum dial delineations 142 and 1A3,

as clearly shown in E at both hands 14:0 and 1 11 thereon,

Figure 1a of the draw 1 the piston D continues its instrokethe ind-i-- catorarmll will" ot'course' be moved to a position tO-indicatethe maximum of the vacuum iirtlie" cylinder at the-limit of the intake stroke, and atwhich pointthelug 7 end ot' the pin 49 will operate-the lever 52 tomove the valve, and uponthestart of'the piston D, on its outward or compression journey, the-valve-72 will move-to align'the' groove SOwith the port 75'and transmit the rising air pressure in the cylinder thru" the conduit 85? into the gauge N for operating the indicator hand 140- to indicate the ext'entofsuperatmospheric air pressure'in the low' pressure orsingle stage cylinder,

I-n-cvent of leaky'paok-ing rings, the pump does not make the full Stroke on t-he high pressure side of the cylinder, and of- 'courses leaky valves and clogged 'air passageways as well as clogged strains will show up in the reduction ot'the pressures on thega'uges. Zlh'e-strokeis accurately measured by'reason oft'the riding 'ofthe header extension 'pin' 49" along: the slot" to indicate/on the graduationson the exterior ofthebarrel 38; as'illus'trat-' edJin' F-igure -2;'the= effective length ofthe stroke; Ifthe stroke is not'of the desired length, it isreadilyapparentthat the pump isinefli'cient' in producing the=full amount of pressure. Insofar as the highpreSsure-cylindenoperation of the deviceAisconcerned, the gauge will show the number "of'pounfds" the'pum'p is receiving and discharging.

Various changes 'in' the' shape; Size, and arrangement" of parts may be made to the forms of invention herein shown and described, without departing from the spirit of th'e same "or the'scope of'the claims: 7

1. n1: combinationwitlr a cylinder having a piston therein, agauge, means connecting the gauge withtthe cylinder forinclicatingpressures existing inthecylinder, and means operati'vely following the piston for cutting the gauge into operation at the limits of travel of the piston" to' determine air pres sures existing in'thecylinder with respect tovtlie location of. the piston-in the cylinder.

2. In combination with an air cylinder havingan openingztlieret'o and a PlSt'OIl'OP- crating in the cylinder, a. reciprocatingconstruction, guide means mounted in the open-- in'g otsaid cylinder for guidingireciprocati'on of'the said;reciprocating. construction, theflatterbeingconstructed to follow the piston during its travel in said cylinder, a

rod into such" engagement With gauge, and means between the gauge and the reciprocating"construction: for causing-f air pressure' from the cylinder to operate; the gauge==ati the limitspf movement of the p1ston ini-.-said cylinder.

3. 111 combination. with; acylinder havingacha-mbeivtherein,- and avpiston travelingini said chamber; means associated: with the cylinder and piston to record pressure in the;

cylinder only: at' the extreme endof each single stroke ot' the piston;

In combination with a cylinder having 3,: piston therein, and a: piston: rod connect.-

ed therewith, means for connection with the cylindenat' the oppositeiside'of the piston from: the piston rod for. cooperation with, the piston duringmnormal engine operation to measure' the stroke of the piston-in: the; cylinder chamber.

5; In combination with aicylinder having a; chamber therein: and a piston-traveling in said 'chamber, a pressure gauge including me ans for in'depen dently and' 1 simultaneously recording: a pluralityof pressures, means to connect!" the pressure gaugewith the, chamber of the cylinder to-transmit pressure to the pressure gauge, valve means for regulating the admission of pressureto one or the other of the indicating means of the prossureigauge, and means: connecting. the lastmentioned-valve means with the piston for operation of; thevalve means torecord pressures: existing in: the cylinder'at. different' locations during theitravel of the piston;

6; In combination with a. cylinder includ ing az piston operating therein, a: guide housing connected with the cylinder, a rod-reciprocable' in saidguide housing,- spring; means carried: by the? guide housing: for nor:

'mally urging-r the rod; against the piston: in

thezcylinder; andumeanstassociated with the guide housing and the rod for indicating the extent? of travel: of: the rod along the guide housing during piston operation. 7 e 71. Inrcombination: with: a locomotiveair compressor including at cylinderhaving" a chamber: therein and a piston; operating" in said'ch'amber; saidichamber having anorifice openingtherein", a tubular body, for detach-- able connection in the orifice opening, a rod slidable in said body for engagement against the piston in the; cylinder, andspring meanscarried by-the body for urging the the piston said body' and rodi having means-thereon to indicate 1 to an observer the extent of travel of the-rod with t-he'piston with respect to the body. j I

8;! Incombination: with i a cylinder having a chamber therein, a piston slidable in said chamber; arode-means'Imounting; the rod to follow with the piston during operation in the cylinder,'. means associated with the "rod to measune t'heis-trokerofithe piston dur the cylinder chamber to one of the indicating devices of the gauge means at one end oi. the piston travel and with the other indicating device at the other end of the-piston travel. t

9. In a device for determining the efficiency of pressures within cylinder chamhers and eiliciency. of pistons operating therein, the combination of a supporting housing, a rod reciprocating in the supporting housing, a valve, and means associated with the valve and with the rod :tor operating the valve at predetermined limits of movement of the rod in the housin 7 10. In a device for determining the efficiency of pressures within cylinder chambers and efficiency of pistons operating therein, the combination oi a supporting housing, a rodreciprocating in the supporting housing, a' valve, meansassociated with the valveand with the rodi or operating the valve at predetermined limits or movement of the rod in the housing, and a spring forcing the rod in one direction along the housing. s i 1 11. In a device for determining the efliciency of pressures within cylinder chambers and etliciency or pistons operating therein, the combination of a supporting housing, a rod reciprocating in the supporting housing, a valve, means associated with the valve and with the rodforoperating the valve at predetermined limits of movement of the rod in the housing, and an air pressure gauge including a plurality of independent measuring mechanisms, said valve including means to direct pressure first into one and then into the other of said measuring mechanisms during travel of the rod in its housing. 4

' 12. In combination with a high pressure 0 linder including a chamber, having-la piston slidahle therein and an opening in said chamber, a body detachable in said opening, a rod, means slidably mounting the rod in said body, a spring normally. engaging the body to urge the rod into engagement with said piston, means carried by said rod including an extension, a valve slidably asso, ciated with said body, moving the valve at the limits of movement of said red as determined by the piston, said trip means being operated by said extension above mentioned.

13. In combination with an air cylinder having a'piston therein, a housing connected with the cylinder having a'plurality of ports communicating with the cylinder, means slidable in the housing with the piston travel, a valve, a gauge having a plurality ofindependently operable indicating mechanisms, sai valve upon movement extension ot said rod and trip means for.

being adapted to communicate one or the" other of said ports of the housing with the indicating mechanisms of the gauge, and

means associated with said valve andthe means which moves with the piston to cause the operation of said valve for transmitting pressures from the cylinder chamber to the, air gauge at predetermmed posit ons oft-he piston travel.

14. In a device ofthe class described the combination of a supporting body construction having a passageway therethrough, rod slidable in said passageway havinga headed extension projecting thru the body construction, a spring operating on the rod for forcin g the same in one direction, slidably carried by line parallel with movement of the rod, a

valve rod connected with said valve, levers. pivotally mounted with respect to thebody construction at spaced points therealong, said levers being operated by the headed during the movement of the rod, said levers having connections with the valve rod to move the valve upon movement of the levers. v

15.. In combination with. a cylinderincluding a piston, a device for measuring the effective stroke of the piston and the pressure within the cylinder comprising means to follow the piston to measure thestrokc thereof, an air gauge, means connecting the a valve the body construction in air gauge with the cylinder to permit air to low from the cylinder to the airgauge, a valve in said last mentioned means, and means associated with the valve and. the means which follows with the piston tomeasure the stroke thereof in order to valve regulate the admission of air from the cylinder to the gauge.

16. In combination with a low pressure cylinder having a piston slidable therein, a gauge device includingindicating means for determining pressure and indicating means for determining the extent of a vacuum, a valve, and means associated with said valve and gauge device and with the piston for valve. regulating admission of pressure or suction from the cylinderto the indicating means of said gauge device.

. 17 In a device "for testing superatmos ioo super-atmospheric pressure indicatingmechanism therein and also a subatmospheric pressure indicating mechanism therein- 1ndependently operable with respect to the first mentioned indicating mechanism, {and means connected with the gauge for operaably connecting either the subatmospheric pressure indicating mechanism or the superatmospheric pressure indicating mechanism to a cylinder independent of the other in an oi 'ierative relation.

JAMES W. HANNAN. 

